class DNode{
    DNode prev;     //上一个结点
    DNode next;     //下一个节点
    int value;

    public DNode(DNode prev, DNode next, int value) {
        this.prev = prev;
        this.next = next;
        this.value = value;
    }
}


class DoublyLinkedListSentinel{
    DNode head; //头哨兵

    public DoublyLinkedListSentinel() {
        head = new DNode(null,null,666);
        tail = new DNode(null,null,666);
        this.head = head;
        this.tail = tail;
    }

    DNode tail; //尾哨兵
}

public class DoubleList {
    //带头结点的双向链表
    public static void main(String[] args) {

    }
}
